(i) Field of the Invention
The present invention relates to a dry cleaning method wherein at least two kinds of solvents are used.
(ii) Description of the Prior Art
For the understanding of a conventional dry cleaning technique, a dry cleaning process of using solvents other than turpentine will be described in reference to FIG. 6 in which the conventional dry cleaning system is shown. First, clothes 2 are thrown into a treating tank 10 by opening a door 1, and after the door 1 has been shut, the operation of the dry cleaner is begun. Afterward, a cleaning treatment generally makes progress in the following order.
(1) A solvent 4 is pumped up from a solvent tank 3 via a valve 5 by means of a pump 6 and is delivered in a predetermined amount to the treating tank 10 through a route consisting of a valve 7 and a filter 8 or a route consisting of a valve 9.
(2) A treating drum 11 is slowly rotated, and the solvent 4 is then circulated through a circuit consisting of the treating tank 10, a button trap 12, a valve 13, the pump 6, the valve 7, the filter 8 or the valve 9 in order to wash the clothes 2.
(3) The solvent 4 is discharged through a route consisting of the treating tank 10, the button trap 12, the valve 13, the pump 6, a valve 14 and a distiller 15. Afterward, the treating drum 11 is rotated at a high speed to centrifuge the solvent 4 present in the clothes 2, and the centrifuged solvent 4 is then discharged in like manner.
(4) The preceding processes (1) and (2) are repeated.
(5) The solvent 4 is discharged to the solvent tank 3 through the treating tank 10, the button trap 12, the valve 13 and the valve 5. Afterward, the treating drum 11 is rotated at a high speed to centrifuge the solvent 4 present in the clothes 2, and the centrifuged solvent 4 is discharged therefrom.
(6) The treating drum 11 is slowly rotated again, and air is circulated in the direction of an arrow 20 between the treating tank 10 and a recovery air duct 19 consisting of a fan 16, an air cooler 17 and an air heater 18, whereby the clothes 2 are dried. A solvent gas vaporized from the clothes 2 is condensed in an air cooler 17, is then delivered to a water separator 22 via a recovery passage 21, and is afterward introduced into a clean tank 24 through a solvent pipe 23.
(7) When drying has been over, dampers 25, 26 are opened as depicted by dotted lines in the drawing, and fresh air is taken in through the damper 25. Further, the uncondensed solvent gas which has not been recovered in the air cooler 17 is discharged through the damper 26 in order to take away the odor of the solvent in the clothes 2.
(8) The solvent 4 forwarded to the distiller 15 in the preceding process (3) is evaporated, and is then condensed in a condenser 27. The condensed solvent 4 is introduced into the clean tank 24 through the water separator 22 and the solvent pipe 23 and is then returned to the solvent tank 3 over an overflow partition 28. In this connection, the water separated by the water separator 22 is discharged from the system through a water pipe 29.
Another dry cleaning process of using turpentine (an oil series solvent) is shown in FIGS. 7 and 8. In general, the turpentine dry cleaning apparatus is composed of a washing and desolvating tank 100 shown in FIG. 7, which is similar to the treating tank shown in FIG. 6, and a drying exclusive tank 200 in FIG. 8 (which is called a tumbler). In the washing and desolvating tank 100, the same procedure as the above-mentioned washing processes (1), (2) and (5) of using the other solvent is taken, whereby all the processes are over. Incidentally, the turpentine dry cleaning method generally contains no distillation process, and in many cases, the purification of the solvent 4 is carried out by using a filter 8a which is packed with an aliphatic acid adsorbent such as porous alumina and a decolorant such as activated carbon.
Next, the desolvated clothes 2 are taken out by opening the door 1, and after the opening of a door 1a of the tumbler shown in FIG. 8, they are thrown into a treating tank 10a. In the tumbler, the outside air 20a is taken in through an inlet duct 19a by a fan 16 and is heated by an air heater 18, and the heated air is then delivered to the treating tank 10a. The solvent 4 in the clothes 2 is evaporated and is then discharged from the system (to the outdoors) through an outlet duct 19a, whereby drying is over.
The general dry cleaning processes of using various solvents have now been described above, but at present, in the dry cleaner in which these solvents can be employed, the washing and drying method of using each solvent has been independently employed, whatever solvents are selected.
Table 1 compares typical physical properties of the solvents often used presently. Further, Table 2 compares features, restrictions, faults and the like of the solvents regarding the dry cleaning on the basis of their physical properties shown in Table 1.
In order to apply to presently diversified materials, processings and forms of clothes, it is necessary to use two kinds of perchloroethylene dry cleaner and Flon 113 dry cleaner, or three kinds of above cleaners and 1,1,1-trichloroethane dry cleaner. If two or more kinds of solvents are used in the conventional apparatus, purchase funds, occupation space, volume of facilities, and the like will be increased, and maintenance work will be complicated. These facts are of great concern to the cleaning trade.
FIG. 5 compares general washing and drying processes in the cases of using perchloroethylene, 1,1,1-trichloroethane, turpentine (oil series) and Flon 113 which are now widely employed. As shown in this drawing, all the methods, except for the Flon 113 method, take about 50% of the whole treatment time to accomplish drying, which fact is an obstacle to recent needs of shortening the treatment time. In addition thereto, the dry tumbling for a long period of time has a bad effect on the clothes at times, and, for example, hairiness and shrinkage of the clothes tend to be caused thereby.
TABLE 1 ______________________________________ Boiling Specific point gravity Ignition (.degree.C.) (g/cc) KB value point ______________________________________ 1,1,1-Trichloro- 74 1.35 124 Not burnt ethane Perchloroethane 121 1.62 90 Not burnt Furon R113 47.5 1.58 31 Not burnt Turpentine 150-200 0.8 31 38.degree. C. (oil series) ______________________________________
The KB values in Table 1 are scales for representing relative dissolving powers of the solvents.